From an absolute individual, and at a species level, we can’t always act in our own best interests. At the highest abstract levels, this is subsentient behavior. People still starve to death. We turn to primitive violence constantly. Our entire reason to avoid large scale conflict is by threatening a massive bottleneck, if not full extinction, of the species with atomic weapons.
On the individual level, no one is massively altering their lives for sustainability and the vast majority are willing to exploit those outside of their limited tribal sphere. Our evolutionary tribal scale mental scope is itself a subsentient behavior. These are but a few examples.
I’ve been writing for fun and exploring this in some depth in a distant future hard sci-fi universe. True sentience is a very high threshold. I don’t think humans will ever be capable of such behaviors, even in a post scarcity world. We lack the mental scope and can’t see completely past the animalistic needs. We are all in conflict internally. Most conflict is just beyond our conscious thoughts.
Looking up and thinking about cognitive dissonance and the resulting behaviors can reveal a lot in this conflict/sentient awareness space.
I’ve personally experienced physical disability long term, and a lot of the uglier side of the present state of medicine, science, and the failures of government in a place that is likely one of the better, and is still terrible. Such experiences shine a light on the true nature of the present human condition in ways most people never need to come to terms with in life. I mean Neanderthals provided food and shelter for their disabled (like Nandy) 45k+ years ago, and I’m looking at likely homelessness within the next 10 years along side the 100k+ other homeless in the greater Los Angeles area. That last sentence alone is proof of subsentient behavior.